On September 3, 2004, approximately 0900 central daylight time, a tailwheel equipped Senior Aero Sport D-260 single-engine airplane, N89JJ, registered to and operated by the pilot sustained substantial damage when it impacted a culvert during landing roll on runway 17 at the Aero Country Airport (T31), near Mc Kinney, Texas. The private pilot, sole occupant of the airplane, was not injured. Visual meteorological conditions prevailed, and a flight plan was not filed for the 14 Code of Federal Regulations Part 91 personal flight. The cross-country flight originated from the Hidden Valley Airpark, near Lake Dallas, Texas, at 0845, and was destined for T31. The 827-hour pilot reported in the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2) that after landing within the first 1,000 feet of Runway 17 slightly right of runway centerline, the airplane was rolling out onto the asphalt portion of the runway. Subsequently, the right main landing gear struck a culvert off the right side of the edge of the runway, nosed over and came to rest inverted. T31 features a single runway, 4, 005-feet in length, and 40-feet wide, oriented on a heading of 350 and 170 degrees respectively. The first 1,000 feet of Runway 17 is composed of a grass surface and is slightly wider than the remaining 3,005 asphalt surface, which is 40-feet wide. A drainage culvert is installed underneath a taxiway connecting the runway to a parallel taxiway at the start of the asphalt surface. The pilot stated that the wind was variable at 3 knots at the time of the accident. Examination of the airplane by the Federal Aviation Administration (FAA) inspector revealed the right main landing gear was separated from the fuselage. The vertical stabilizer and rudder were bent and the left wing spar was cracked.